Subclinical Defects in Renal Regulation of Acid Base Balance in Children With Recurrent Urinary Tract Infections

Abstract

Summary Renal control of acid base balance has been evaluated in children with recurrent urinary tract infections. For reference a group of normal children has also been studied. The studies were performed before and after a single oral intake of ammonium chloride. The following parameters have been determined: the maximal ammonia excretion and the relationship between blood total CO2 concentration and urine pH. The maximal ammonia excretion was found to be reduced in proportion to the filtration rate. All the patients with low to moderately reduced filtration rates and four of the patients with subnormal to normal filtration rates demanding larger reduction in blood total CO2 concentration than the normal controls before a fall in the urine pH could be observed. This finding was taken as a sign of reduced bicarbonate threshold. It is therefore suggested that the reabsorption of filtered bicarbonate is one of the most vulnerable function of the kidney in recurrent urinary tract infections.

A Modification of the Short Ammonium Chloride Loading Test in Children

“…As shown in the studies of Edelmann et al [3] and Berg et al [1] in the first collections after the administration of ammonium chloride, the urine pH remains high and the ammonia excretion low. So it is necessary, if we would obtain valuable information about renal acidifying mechanisms in infants, to collect their urine through indwelling urethral catheter.…”

Renal Acid-Base Titration Studies in Infants with and without Metabolic Acidosis in the Postneonatal Period

“…These could be collected generally at 30-90-min intervals. Control bacteriologic cultures were performed in every case in order to exclude urinary tract infection that might influence the renal acidification [2]. From 7 to 9 AM, two control urine specimens were collected, and at 8 AM an arterialized capillary blood sample for analysis of the preloading acid-base status was obtained as described in a previous report [33].…”

“…Several factors may influence the excretion and reabsorption of bicarbonate and thus the renal bicarbonate threshold, e.g., ( I ) activity of carbonic anhydrase [36]; (2) alterations in renal metabolism and in kinetics of enzyme reactions [20]; ( 3 ) disturbances in potassium balance [24]; (4) morphologic glomerulotubular imbalance [5, 81 ; ( 5 ) changes in extracellular volume [16,21,26,27,371.…”

“…However, adequate data are not available to permit a definite statement about the significance of the renal function in this respect during the early postneonatal period of life, i.e., between 1 and 4 weeks of age. The present investigation was therefore designed ( I ) to study the renal hydrogen ion excretion after an acute ammonium chloride load as well as the renal response to bicarbonate titration at 1-3 weeks and 4-6 weeks of life in the same infants, and (2) to evaluate these renal functions in relation to the occurrence of so-called late metabolic acidosis.…”

Renal Function Tests in Nonacute Recurrent Urinary Tract Infections in Children

“…They were all without any clinical or bacteriological signs of infection the last two months prior to the presented studies. The results from the clearance studies have been given in previous reports (2, 3, 5, 6). The blood and urine tests were obtained at the same period of time (within 2 weeks) as the clearance studies.…”